Embodiments of the present disclosure relates to a lifting-off method and a manufacturing method for a thin film transistor (TFT) array substrate.
The lifting-off method is an important technology used for preparing patterns with a photoresist mask. The lifting-off method is a technology, in which photoresist is peeled off together with the film deposited thereon without tearing or damaging other film patterns on a substrate during removing the photoresist. The lifting-off method is widely used in the microelectronics manufacturing field such as the semiconductor manufacturing field.
By taking a thin film transistor liquid crystal display (TFT-LCD) as an example, which is formed by assembling an array substrate and a color filter substrate with a liquid crystal layer injected therebetween, a lifting-off method is usually used for forming ITO (indium tin oxide) pixel electrodes in manufacturing the array substrate. In detail, a passivation layer is deposited on a glass substrate. After forming a passivation pattern comprising a via hole, photoresist in the non-pixel-electrode areas is remained and an ITO pixel electrode layer is deposited thereon. The remained photoresist is removed through a lifting-off method together with the ITO layer thereon, thereby forming a pixel electrode pattern.
In a conventional lifting-off method, generally the remained photoresist on the substrate is heated first to have the photoresist contract or shrink, whereby the thin film adhered to the photoresist collapses and cracks so that the underneath photoresist is exposed. Next, the exposed photoresist is brought to be in contact with a lifting-off solution by means of spraying the lifting-off solution at a high pressure or immersing the substrate into the lifting-off solution in an ultrasonic treatment. Under the action of the lifting-off solution, the photoresist is removed so that the film attached thereon is also taken off, thus a lifting-off effect is achieved. However, the shrinkage of the photoresist is limited since the amount of the exposed photoresist due to collapse and crack is relatively small, that is, the amount of the photoresist in contact with the lifting-off solution is relatively small, thus the interacting force between the photoresist and the lifting-off solution is not enough, and thereby the process time is relatively long and the lifting-off effect is relatively poor.